Which do you prefer - just the chainring or chainring/bashguard combo?- Mtbr.com
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  1. #1
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    Which do you prefer - just the chainring or chainring/bashguard combo?

    I've got to figure out what to do on my Inbred 29er - I plan to run it in single speed mode and I've got a set of Truvativ Stylo crankarms to work with.

    Option 1- get a 32T chainring and some of those shorter bolts and run it all the way outside

    or

    Option 2 - go with a 32T ring and a bashguard to protect it - probably more costly unless I use the 36T Blackshpire guard I already have - but that's kind of a big guard to protect a 32T ring.

    Are there any advantages or disadavantages to running the chainring all the way out on the cranks with no bashguard - does this allow for a better chainline perhaps?

    Or is it the safer route to run a ring and guard combo?

    Many thanks.

    Mark

  2. #2
    drev-il, not Dr. Evil!
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    Quote Originally Posted by MMcG
    I've got to figure out what to do on my Inbred 29er - I plan to run it in single speed mode and I've got a set of Truvativ Stylo crankarms to work with.

    Option 1- get a 32T chainring and some of those shorter bolts and run it all the way outside

    or

    Option 2 - go with a 32T ring and a bashguard to protect it - probably more costly unless I use the 36T Blackshpire guard I already have - but that's kind of a big guard to protect a 32T ring.

    Are there any advantages or disadavantages to running the chainring all the way out on the cranks with no bashguard - does this allow for a better chainline perhaps?

    Or is it the safer route to run a ring and guard combo?

    Many thanks.

    Mark
    I'm ungraceful sometimes, so I prefer the guard.
    "Keep your burgers lean and your tires fat." -h.d. | ssoft | flickr

  3. #3
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    If you are ungraceful then I'm a total hack. Maybe I should just use the 36T guard.

    Or should I just buy that Bikeman.com SS crankset for $59.00 ......decisions decisions.

  4. #4
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    Hold a 36t guard up to a 32, the difference will be very small. Use the Blackspire, nothing finer.

    For AZ rocks, I find a bash mandatory.

  5. #5
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    Okey dokey that settles it then. I'll get a new SS ring and use the blackspire.

  6. #6
    CB2
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    I used to ride without a bash-guard because I liked the way it looked better, but after tweaking a couple of chains, I don't consider it an option for the areas I ride (which are also the areas you ride).
    I'd use the bash-guard you've already got.

  7. #7
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    Thanks a lot - did you get my second email??

  8. #8
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    Another minor consideration............

    If your chainstay affords clearance for you to run your ring in the "middle" position and your chainline is good this way, go for it. There will be slightly less stress on the frame and drivetrain because the closer the chain runs to the center of the bike, the less stress your bike will have to endure while you're torquing up hills.

    It's not a real world big deal, but for the sake of illustration, imagine if your spindle were so long that your cranks stuck out a foot from the BB shell (and your rear cog lined up so the chainline was spot on). You can imagine how much stress this cantilevered situation would place on the drive system and especially the frame's BB shell. So the closer to the bike's centerline you can run your chain, the [slightly] better for everything.

    --Sparty
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  9. #9
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    Thanks Sparty! that puts the icing on teh cake then.

  10. #10
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    I just run the ring in the inner postion, and no bash. The chain is plenty smooth enough to slide over logs, and I havn't had issues bending rings. My SS just uses an XT hub with spacers, so I can get the chainline just right, regardless of where the ring is.

  11. #11
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    Quote Originally Posted by Sparticus
    If your chainstay affords clearance for you to run your ring in the "middle" position and your chainline is good this way, go for it. There will be slightly less stress on the frame and drivetrain because the closer the chain runs to the center of the bike, the less stress your bike will have to endure while you're torquing up hills.

    It's not a real world big deal, but for the sake of illustration, imagine if your spindle were so long that your cranks stuck out a foot from the BB shell (and your rear cog lined up so the chainline was spot on). You can imagine how much stress this cantilevered situation would place on the drive system and especially the frame's BB shell. So the closer to the bike's centerline you can run your chain, the [slightly] better for everything.

    --Sparty
    Doesn't that suggest using the shortest possible crank spindle as possible (which would require replacing the BB), rather than putting the chainring inboard as far as possible on the current crankset?

    Unless the distance between the cranks/pedals is reduced, the same practical forces (the rider stomping on the pedals) are going to be applied on the lever (the crankarm).
    Last edited by anotherbrian; 02-23-2007 at 02:05 PM.

  12. #12
    Out spokin'
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    I think I see what you're saying

    Quote Originally Posted by anotherbrian
    Doesn't that suggest using the shortest possible crank spindle as possible (which would require replacing the BB), rather than putting the chainring inboard as far as possible on the current crankset?

    Unless the distance between the cranks/pedals is reduced, the same practical forces (the rider stomping on the pedals) are going to be applied on the lever (the crankarm).
    Maybe you're right. But even if you are, I don't think this negates my contention that the farther outboard the chain runs, the more chain tension between the ring and cog tries to fold the rear triangle in half. This is regardless of Q factor.

    I think we're saying different things. Might we both be right?

    --Sparty
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    We don't quit riding because we get old.
    We get old because we quit riding.

  13. #13
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    I'm not a mechanical engineer, but I play one on TV

    I've put the ring on the inside of the spider rather than the outside for a few reasons, but to address Sparty and anotherbrian, I think the ideal is the ring as close as possible to the center of the crankarm, and that whole assembly as close as possible to the center of the BB shell*. To extend Sparty's first example (which is a good one), if your spindle were so long that your cranks stuck out a foot from the BB shell but your cog was in a normal position, and you used really long bolts on the spider to move the ring back very close to the BB shell, you wouldn't achieve anything but amplification of flex. Better to have the whole works nice, tight and together (which is what has already been said, I guess). If all other things were equal, I would most likely put the ring on the inside of the spider. If only there was some way to have the drivetrain run right down through the middle of the bike and my rear rim. I'm working on it

    *admittedly, the bike should also fit the rider, good q-factor, bla bla bla

  14. #14
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    aesthetics

    I go without a bashguard because i like the cleaner look. also, easier cleaning of the chainring. but i don't mash over logs and rocks that much, and if i did, i'd put the bashguard back on.

  15. #15
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    Quote Originally Posted by anotherbrian
    Doesn't that suggest using the shortest possible crank spindle as possible (which would require replacing the BB), rather than putting the chainring inboard as far as possible on the current crankset?

    Unless the distance between the cranks/pedals is reduced, the same practical forces (the rider stomping on the pedals) are going to be applied on the lever (the crankarm).
    I see your line of thinking, but it's not the case. There are still increases in the leverage point when moving the chainring out further from the BB shell.

  16. #16
    i don't give a shift
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    Quote Originally Posted by Cygnus
    I go without a bashguard because i like the cleaner look. also, easier cleaning of the chainring.
    Exactly, plus the weight-saving. I always run my chainring in the outer position in combination with a narrow road BB.
    blogging @29in.CH

  17. #17
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    I go without a bashguard but use a thicker chainring (for 1/8" chain only).

  18. #18
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    Quote Originally Posted by mud'n'sweat
    I see your line of thinking, but it's not the case. There are still increases in the leverage point when moving the chainring out further from the BB shell.
    True, true, but with the popularity of external bearing cranks it is a wash maybe?

    Mark, I have a bash that came with my stylo 1:1's and it runs the chainring and the bash using the same bolts....can you noy do that with the sylos you have? I was going to leave the guard off, but after looking at Dan's ring, it's going back on. Too many rocks here in ol' Maine.
    unityhandbuilt

  19. #19
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    Bash guard

    Bash guard all the way. Rocks are sneaky and walking out with a bent ring sucks.
    luck favors the prepared.

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